Explorations of time in the world of physics

The notion of time and precisely what it is has always been a subject for debate, whether in philosophy, physics or daily life Time has remained somewhat of a mystery to society for as long as we can remember; we know it as a measure that helps order and keeps track of events, but we still do not fully understand it We believe there is a past, present and future, but are the past, current and future simply subjective? We seem to experience time as a moving present, but is this just an illusion? So, while this remains a great mystery for some of the greatest physicists, this article will include some of the most famous and relevant theories surrounding time to understand this mysterious phenomenon better

Various theories have been investigated and developed throughout history to explore time by well-known scientists like Isaac Newton, Albert Einstein, Erwin Schrödinger and Stephen Hawking (all four of the world’s most notable time physicists) One of the first to famously apply for his work successfully to time physics was Sir Isaac Newton He did this by laying down the foundation for the mechanics and mathematics of time Newton believed time to have a linear relationship with space (or distance travelled). His important discovery of gravity would then help Albert Einstein further with his investigations Hence, Newton’s theories became outdated when Einstein proposed his theory of relativity

Albert Einstein’s investigations led him to believe that time is relative to the physical universe- a physical universe defined by the presence of movement, matter and consciousness. He felt the passage of time would differ for objects moving at different velocities through space He introduced a thought experiment through the theory of relativity to explain what he meant, called “the twin paradox” In physics, this “twin paradox” (which is often used to explain special relativity) involves identical twins: one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more; Einstein used this to demonstrate the curious manifestation of time dilation His theory of relativity defined time as a fourth dimension, thereby transforming threedimensional space into four-dimensional spacetime Relativity is the idea that the faster you travel through space, the slower you move through time, and that gravity travels in the form of waves According to Einstein’s calculations, an event that took one day to complete by someone standing on Earth would take 12 hours to complete if they were travelling at 87% of the speed of light In 1915, he further unified space, time and gravitation with his general theory of relativity- showing that warps and curves in space and time are responsible for the force of gravity

Erwin Schrödinger was also around at the time of Einstein and played a crucial role in the investigation of time- he was known as the ‘father of quantum mechanics ’ “Schrödinger’s cat experiment” has become one of the most well-known paradoxes in quantum theory- it was meant to show that quantum mechanics does not necessarily always apply to more critical and concrete things Furthermore, the famous Schrödinger equation explains how wavelength changes over a period of time and the solutions to his equation, unlike the solutions to Newton’s equations, are wave functions that can only be related to the probable occurrence of physical events

Lastly, Stephen Hawking was the most recent of these scientists and is most known for his contributions to cosmology, gravitation, quantum theory (related to black holes), thermodynamics and information theory He discovered the laws of black hole mechanics, which would also be essential in physicists’ studies on time. Hawking believed that according to the laws of physics and contrary to intuition, black holes should radiate away energy and slowly evaporate; he came to this conclusion by extrapolating information from well-established theories of quantum mechanics and thermodynamics Hawking had an idea that if a book were thrown into a black hole, the information inside would disappear forever However, this created a paradox, as laws of physics and quantum mechanics, in particular, do not allow data to be destroyed

A more recent theory has started to emerge lately, and that is string theory (with particle physics) This theory attempts to merge quantum mechanics with Albert Einstein’s general theory of relativity, and the potential of using this theory to try and explain time has also unfolded. In the 1980s, physicists realised that string theory had the potential to incorporate all four of nature’s forces: gravity, electromagnetism, strong force and weak force- and all types of matter in a single quantum mechanical frameworksuggesting that it may be the long-sought for unified field theory! While string theory is still a vibrant area of research that is undergoing rapid development, it remains primarily a mathematical construct as it has not yet experienced any experimental study, which is why string theory is so hard to prove, as we currently do have not got enough resources to establish or experiment with this theory

In conclusion, the theory of relativity is widely accepted by many physicists as the possibility of time travel Hawking also agreed with this idea, as he saw that a black hole of such size has a profound effect on time, making it a ‘natural time machine’ It is believed that theoretically, black holes can create a tunnel through space-time and that, technically, laws of physics do not prevent time travel Whether we want to travel into the future or the past, it comes down to the ability to travel close to the speed of light We have still not found that one equation in physics which unifies all fields However, string theory could be a way forward if we develop the resources in the future It is fascinating to observe that specific laws of physics may change over time However, time is the only aspect of the universe that remains timeless As Albert Einstein famously stated: “the only reason for time is so that everything doesn’t happen at once ”